A COMPARISON OF CENSUS JOURNEY-TO-WORK AND MODEL-GENERATED TRANSPORTATION DATA IN THE PUGET SOUND REGION

Journey-to-work trip data from the 1980 Census and output from the Urban Transportation Planning System are compared for the Puget Sound Region in Washington State. The purpose of this comparison is twofold: to identify where regional transportation models may need adjustment and to determine whether census journey-to-work data are a valid substitute for large-scale origin-destination surveys. Home-based total work trip tables and home-based transit work tables from the census and the model are compared using two methods: a trip length frequency distribution comparison and mapping the differences between the two sets of trip tables using the FLOWMAP mapping program. The trip length frequency distribution comparison shows that census work trips average slightly longer than model trips. FLOWMAP analysis, which maps the differences between the two sets of trip tables, reveals that, for total trips, census trips exceeded those from the model for trips attracted to the central business district of three major cities in the region. A second significant finding in the FLOWMAP analysis is that the model shows a few more longer transit trips than do the census data. An evaluation of census journey-to-work data is undertaken.